Context Diabetic nephropathy in type 2 diabetes mellitus is one of the most serious microvascular complications. Immunoglobulin G (IgG), with molecular weight of 150 kDa, is excreted in urine of normoalbuminuric diabetic patients.
Aims The aim was to compare urinary IgG with microalbuminuria as an early indicator of diabetic nephropathy in patients with type 2 diabetes mellitus.
Settings and design The study was conducted in Zagazig University Hospital.
Materials and methods This case–control study was conducted on 88 type 2 diabetic adult patients who were divided into four groups. Group I: 22 patients with normal albumin creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR), group II: 21 patients with normal ACR (<20 mg/g creatinine) and eGFR (>120 ml/min/1.73 m2), group III: 24 patients with ACR from 20 to 200 mg/g creatinine and eGFR ranging from 60.74 to 102.48 ml/min/1.73 m2, and group IV: 21 patients with ACR more than 200 mg/g creatinine and eGFR ranging from 17.16 to 85.27 ml/min/1.73m2. Patients were subjected to complete blood count, kidney function tests (KFT), urinary albumin/creatinine ratio, urinary IgG/creatinine ratio, random blood sugar, and estimation of GFR by modification of diet in renal disease equation.
Statistical analysis The data were analyzed using statistical package for the social science (SPSS), windows version 17. Description of qualitative variables was done by frequency and percentage. Description of quantitative variables was in the form of mean±SD. χ2-Test, Student’s t-test, analysis of variance (F-test), and correlation analysis were used for analytical examination.
Results High significant difference among the different groups was found regarding ACR (P<0.001) and immunoglobulin G creatinine ratio (IgGCR) (P<0.001). ACR and IgGCR are highly increased in groups III and IV in comparison with groups 1 and II. There was a significant positive correlation between IgGCR and age, diabetes mellitus (DM) duration, serum creatinine (P<0.001), blood urea nitrogen, ACR, and renal sonography, and negative correlation with eGFR (P<0.001), hemoglobin, and serum albumin.
Conclusion IgG appears in urine in early stages of diabetic nephropathy even before microalbuminuria, so we recommend its use to define high-risk patients, allowing prompt interventions.